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Page 894 of 936 Results 8931 - 8940 of 9356

Jerzy Sladek, Marcin Krawczyk
MODELING AND ASSESSMENT OF LARGE CMMs' ACCURACY

In this paper presented is the research on developing of a model of CMM based on application of artificial neural networks. The work focused on developing a conception of large CMMs’ errors. Described here is the large CMMs’ error identification method that utilises standard plate and laser interferometer, and presented are the possibilities of its application for development of measurement machine model. So developed method enables to carry out assessment of large CMMs’ accuracy, while related to it a CMM model is being utilised for the realised measurements’ accuracy assessment.

Dirk Stöbener, Matko Dijkman, Dennis Kruse, Holger Surm, Olaf Keßler, Peter Mayr, Gert Goch
DISTANCE MEASUREMENTS WITH LASER-TRIANGULATION IN HOT ENVIRONMENTS

Tactile distance measurement systems with uncertainties in the micrometer range cannot be used in hot environments with temperatures above 800°C. A green laser-triangulation system with appropriate optical filters can meet these requirements. A measuring system was build up and tested at room temperature and in two different heat treatment furnaces at temperatures up to 900°C. Good linearity of the system and acceptable correspondence between measurements and published reference values could be observed. The results show the suitability of the system for distortion measurements in heat treatment furnaces.

TaeBong Eom, JaeWan Kim
DISPLACEMENT MEASURING SENSOR CALIBRATION USING NONLINEARITY FREE LASER INTERFEROMETER

For calibration of displacement measuring sensors with sub-nanometer resolution, a novel calibration system using laser interferometer was developed. It is directly traceably to the Meter and portable due to use of laser coupled by an optical fiber. And also it has a higher accuracy because of nonlinearity free laser interferometer and compact design. The detailed system and one example of calibration are described. Finally a detailed uncertainty budget is described.

T. Watanabe, H. Fujimoto, K. Nakayama, M. Kajitani, T. Masuda
CALIBRATION OF A POLYGON MIRROR BY THE ROTARY ENCODER CALIBRATION SYSYTEM

In this paper, we propose the new calibration measurement method of a polygon mirror. The measuring method of the conventional polygon mirror that uses an index table needs much technical skill, much time, and the amount of work. We used the Equal-Division- Averaged (EDA) method and have already developed the self-calibration system that calibrates the angle graduation signal of two sets of rotary encoders simultaneously. By combining this system and a polygon mirror, it becomes possible to measure the angle between faces of a polygon mirror. Now, in Japan, the angle traceability system which used the rotary encoder as the base of angle measurement device is established. If this technology is applied and a polygon mirror can be measured, it will make it easy to build a polygon mirror into the same traceability system.

Antti Lassila, Jorma Jokela, Markku Poutanen, Xu Jie
ABSOLUTE CALIBRATION OF QUARTZ BARS OF VÄISÄLÄ INTERFEROMETER BY WHITE LIGHT GAUGE BLOCK INTERFEROMETER

Measurement of a baseline with Väisälä interferometer is a traditional high accuracy length measurement in geodesy. An accurate length up to 1 km is achievable by interferometrically multiplying the length of a 1 m quartz bar. Therefore, the absolute length of the bar should be known with small uncertainty. A measurement setup and procedure for calibration of length of a quartz bar by combined white and laser light gauge block interferometer has been developed. The calibration procedure, results and uncertainty evaluation are presented. A standard uncertainty of 35 nm has been achieved.

Lifong Zou, Dayananda Samarawickrama, Kevin Seymour, Ken Stout
FREE FORM SURFACE MEASUREMENT USING NON-CONTACT MEASUREMENT METHODOLOGY

Quality control is applied to almost every procedure during the manufacturing process in industry. However, it is not used commonly in restorative dental practice. The surface contour or shape of the tooth is very irregular, a 'so called' free form surface. Measurement of such a free form surface needs a specified strategy to satisfy the measurement accuracy. This paper attempts to propose an optimal measurement strategy to measure the occlusal molar tooth surface, in order to achieve a degree of measurement and quality control in restorative dental practice.

Tanfer Yandayan
LARGE MEASUREMENT RANGE MECHANICAL COMPARATOR FOR CALIBRATION OF LONG GAUGE BLOCKS

A new design of mechanical gauge block comparator for calibration of long gauge blocks is described. The comparator is constructed by modification of a commercially available universal length measuring machine. It is able to compare the different nominal size gauge blocks with its 300 mm measurement range. This has the advantage that a reference metric size gauge block can be used to calibrate the inch size square or rectangular section gauge blocks or vice-versa. Line scale of the length-measuring machine, which is calibrated by a laser interferometer and gauge blocks, is used for the measurement of displacement. Calibration procedure adapted from EAL-G21 guideline is described with the aid of the results. The uncertainty of the measurements is evaluated and the parameters, which has influence on the uncertainty, is described in detail. The successful application of the comparator for calibration of metric or inch gauge blocks in different cross sections up to 500 mm or 20 inch nominal size is presented with the results. The uncertainty of the comparator with k = 2 is U = [ 1502 + 0.5 L)²]1/2 nm, where L is the gauge block length in mm. For instance, U is calculated as 292 nm (k = 2) for 500 mm long gauge block.

Sarwat Zahwi, Monier Koura, Alia Mekawi
FACTORS INFLUENCING UNCERTAINTY EVALUATION FOR SURFACE ROUGHNESS MEASUREMENTS

The nominal conditions for measuring surface roughness when using stylus instruments are specified in ISO 3274. Deviations from these nominal conditions lead to significant deviations of the measured roughness parameters. An uncertainty evaluation has been made on five roughness parameters for three calibration standards. The methods and procedures for uncertainty evaluation are to i) calibrate and evaluate the uncertainty in the condition for the measuring instrument, ii) evaluate the influence of each individual deviation on the results of measurement, and iii) combine the effect of these individual uncertainties on the final result of measurement. A study has been carried out on the influence of different contributors on the combined uncertainty associated with the assessment of roughness parameters. From the results the major contributors affecting the uncertainty of measurement on different roughness parameters are given.

A. Titov, I. Malinovsky, C.A. Massone
NANOMETROLOGY REGIME IN LENGTH MEASUREMENTS OF MATERIAL ARTEFACTS WITH NOMINAL LENGTHS UP TO 100 mm

New calibrated double-sided method of interferometric length measurements with quartz reference plate is reported. The method is free from wringing errors, and can be used for the improvement of measurements of material artefacts. Limitations of the interferometric measurements are discussed. Some systematic errors are measured with a sub-nanometer resolution.

K. Umetsu, R. Furutani, T. Takatsuji, S. Osawa, T. Kurosawa
CALIBRATION OF A CMM USING A LASER TRACKING SYSTEM

A new calibration approach of a coordinate measuring machine (CMM) using a laser tracking system is proposed. According to the conventional approach of the laser tracking system, trilateration principle is mainly adapted. Therefore one retroreflector and four laser trackers are required. Though this approach is capable of attaining high accuracy measurement, measuring volume is likely to become smaller due to physical limitations for middle size CMM. Consequentially, we need new approach, which uses the least laser trackers in numbers. In this paper, effective calibration strategy to estimate 21 kinematic parameters of CMM’s axes is described. Additionally to confirm the validity of the proposed approach, the parameters estimation using a ball plate was conducted in parallel. The estimation results by the laser tracker and the ball plate showed good agreement.

Page 894 of 936 Results 8931 - 8940 of 9356